A halo orthosis minimizes motion of the cervical spine after traumatic injury or in recovery after surgery. To immobilize the cervical spine, the halo orthosis provides a rigid structure that fixes the head of the patient relative to the patient's chest. The standard halo orthosis includes a crown or halo ring and halo pins that secure the halo ring to the head of the patient. The basic design of the halo orthosis has changed very little since its introduction in 1959.
Two of the most common problems associated with halo orthoses are pin loosening and/or pin migration (hereinafter referred to jointly and severally as “pin loosening”). To ensure that the head is properly fixed, the halo pins typically must pierce through the skin and rest against or embed in the skull. However, bone remodeling at the pin sites, changes in the elasticity of the head or skull, and/or other physiological changes in the head or skull geometry typically cause the pins to loosen over time. Proactive and/or corrective pin adjustments require undesirably complex and costly follow-up care by highly skilled medical professionals (typically orthopedic surgeons). For the patient, pin loosening can cause significant pain, potential loss of immobilization, and an increased risk of infection.
Indeed, infection is another common problem with halo orthoses. As the halo pins typically pierce the skin, each pin site creates a wound that is vulnerable to infection. Notwithstanding any loosening and/or retightening of the pins, the undesirably high number of pin sites in prior designs adds to the risk of infection.
The application procedures for prior halo orthoses also present problems. Historically, an orthopedic surgeon or team of orthopedic surgeons has been required to manually balance the torque among the various separate pins in order to properly apply the halo. Typically, such procedures are painful to the patient and require significant amounts of time and skill from the orthopedic surgeons.
Thus, there is a need for a halo orthosis that provides reduced pin loosening. Also, there is a need for a halo orthosis that requires a minimal number of pin sites. Additionally, there is a need for a halo orthosis that requires less time and skill to apply.